Saturated Solution
Definition
A solution holding the maximum dissolved solute it can at a given temperature: add more and it just sits undissolved.
Technical definition
A saturated solution contains the maximum solute that can dissolve at a given temperature, existing in dynamic equilibrium with undissolved solute. Its concentration equals the solute's solubility at that temperature.
Example
Stirring sugar into iced tea: at some point no more dissolves and crystals sit at the bottom. The tea is saturated.
Common confusion
Saturated does not mean concentrated. A saturated solution of a barely soluble salt like AgCl is extremely dilute: saturation is relative to that solute's solubility limit.